Has anyone noticed that the 'true' max apertures as indicate by the Tstop is nowhere near the manufacturers claim? The Zeis is closer to a f1.8 lens than f1.4 and the rest fare no better....
T value is not aperture value, an f1.4 lens is a "true" f1.4 if the apparent aperture diameter is focal length divided by 1.4. The T value relates to actual light transmission and is pretty much irrelevant with TTL metering stills cameras.
Aperture value is always lower than T (transmission) value because however good the glass is you always lose some.
Quite a few of the latest EF lenses do seem to have a T value that is the same as the aperture: the 24-70 IS, 40 pancake, 24/28/35 IS primes. These are all slower lenses but it does look like Canon are achieving a very high light transmission efficiency - you know - to make up for the sensor.........
LOL - but a solid point, and part of why I was surprised that the T-stop lagged so much with the Otus 85. I raised the point in my 35IS review that the light transmission between the Sigma 1.4Art and the 35IS wasn't all that big. The 35IS feels like it has a wider aperture than f/2 (although it actually just REALLY has an f/2 aperture, instead of a f/2.3 or such.)
It's probably just me, but I wasn't blown away by the images in the video. Maybe I am now just jaded.
I know what you mean. Several of them seemed really underexposed, but the crops certainly showed the great detail rendering.